It was with regret that we laid down our chopsticks and admitted defeat. It was the unfinished whole crab that hurt the most: chopped up, then flash-fried in a light batter, it lay amid a pungent, rustling nest of dry fried red chillies, garlic, salt, chillies, Szechuan peppercorns, and more chillies, a thrilling mountain of white and red. The shell was soft enough so that you could rip it apart with your teeth, or even squeeze the meat out of the legs, and when you got to it, the ribbons of white crab were sweet and salty and fiery all at once. They offered to let us take the rest home but we both knew it was not the kind of dish that would taste good the next day, so we let it go.

I will just have to return to Gourmet San. It is a small, spartan restaurant on a rather unlovely stretch of east London's Bethnal Green Road (which, to be honest, describes much of the Bethnal Green Road). It is also proof that the relatively recent hunger for genuine Szechuan food, which began with the exciting but pricey Bar Shu in Soho, has reached a certain maturity. Bar Shu is fancy. It has been 'designed', and that is partly what you are paying for when you pick up the hefty bill. Nobody has designed Gourmet San. With this much colour on the plate they didn't need to. It's just a place catering to a particular clientele. Generally I am a little suspicious when Chinese restaurants are venerated solely because so many of the customers happen to be Chinese. I've seen a whole bunch of Chinese people eating at Wong Kei in Soho. That doesn't mean it isn't one of the grimmest Chinese restaurants in Britain, staffed by some truly nasty, aggressive people who have turned intimidating their customers into a sport.

And yet, when the menu is as unfamiliar as this, it is curiously reassuring to look up and realise that you are literally the only two non-Chinese people in there. My companion, Simon, spent some time in Szechuan province last year and, looking at the menu, was able to confirm that it was the real thing, down to the cuts of chicken cooked in coke (yes, really) and the selection of barbecued meat skewers. We tried some lamb's kidneys and a quail and both came heavily seasoned with the same beguiling spice mix of salt and ground cumin. Both were delicious.

As a result of the menu at Bar Shu, many people assume that a lot of Szechuan food is essentially lumps of protein in a swamp of chilli-spiked oil. They are right. Quite a lot of it is. Eat it the wrong way, start spooning the oil down your neck, and bits of you will keep reminding you of your stupidity for days to come. But here we found other things. A cold starter of sliced beef tongue and tripe - offal and gelatinous extremities proving most popular in this sort of joint - came only lightly dressed with chilli oil, and was a satisfying plateful for two men who hate to see any part of the beast wasted. Alongside that a heap of pickled cucumber cut roughly into hunks was not so much a palate cleanser as a palate cooler. It reminded me of that classic Jewish pickle New Green, which is about as unlikely a comparison as you are ever likely to see me make.

As well as the crab, a steal at £11, we ordered a £7 plate of pig's trotters in sugar-sweetened soy, the long-braised flesh pulling away from the knuckles with ease. Piles of stripped bones and crab shells built up around us, and we were happy. As indeed were the staff, who seemed pleased to see us there. A plate of Gong Bao prawns, the shellfish served with chillies and peanuts in a hot, mouth-coating sauce, was as solid a version as you are likely to find. We drank Tiger beer, and regretted that we hadn't brought a few other mouths along with us so that we could have tried one of the big chrome pots of broth rammed with chillies, or shaken down the skewers menu, a detailed affair that makes much of the difference between the back and the front leg of the rabbit. It is probably the only menu of its kind available right now in Britain. What's more, with a few more companions we would have polished off that crab, would have stripped those last gnarly pig's feet to the bone. In short, we would have done this true gem of a restaurant justice.

jay.rayner@observer.co.uk

· Is Gourmet San run by the most modest restaurateurs in Britain? Jay Rayner explains on the food blog